The research objectives include studying several aspects of lymphocyte biology and transplantation immunology. Transplantation procedures will also be employed to elucidate the mode of action of a coat-color determinant in mice. Specifically, the projects deal with (1) the influence of Ag-B genotype on the survival of rat lymphoid cells in adult mice and on their capacity to induce graft-versus-host reactions when inoculated into neonatal mice of different genotypes; (2) further studies on the male specific antigen of mice and rats; (3) further studies on the maintenance of tolerance of skin homografts; (4) attempts to alleviate streptozotocin- induced diabetes in rats and diabetes of genetic origin in mice with islet transplants; and (5) transplantation studies to elucidate the mode of action of steel on melanogenesis in mice.